The power toothbrush includes a handle (12) and a workpiece assembly (18) which includes a brushhead (20) at a forward end thereof. The toothbrush further includes a drive assembly (14) which includes a DC motor (26) having a rotating output shaft (41) and a mounting assembly (28) for flexibly mounting the motor to the handle. The drive assembly includes a torsion spring member (64), an eccentric member (52), a coupling member (44) for connecting the rotating output shaft of the motor to the rear end of the eccentric and a hub member (62) forward of the eccentric, wherein the other end of the eccentric extends to and is mounted to the hub member. The torsion spring extends between the motor mount and the hub member. In operation, the rotating eccentric excites a desired resonant mode in the torsion spring, resulting in a sweeping back and forth action of the workpiece assembly and the brushhead.